Reopened Unassigned: Value is clear when focus to MaskedEditExtender [27966]

Hi,

I have just updated to using ajax 15.1.3 and found that behavior on MaskedEditExtender is changed compared with previous version.
Steps:
1. Typing value to mask input
2. Focus out mask input
3. Focus again on mask input >> value is cleared

At step 3, the value is not cleared on previous version.
I'm not sure this is new issue or it's as intend.
Could you please explain for me.

Thanks